A transparent conductive film including a transparent plastic substrate and a transparent and low resistance thin film laminated on the transparent plastic substrate has been widely used for application in electric and electronic fields, such as application of utilizing the electroconductivity of the film, e.g., a transparent electrode of, for example, flat panel displays such as a liquid crystal display and an electroluminescent (EL) display, and a touch panel.
A resistive film type touch panel includes in combination a fixed electrode obtained by coating a glass or plastic substrate with a transparent conductive thin film, and a movable electrode (film electrode) obtained by coating a plastic film with a transparent conductive thin film, and the resistive film type touch panel is used by overlapping thereof on an upper side of a display body. The film electrode is pressed with a finger or a pen, so that the fixed electrode and the transparent conductive thin film of the film electrode are brought into contact with each other to serve as an input for recognizing a position on the touch panel. In many cases, a pen applies stronger force on the touch panel than a finger. Successive input on the touch panel with a pen sometimes causes a rupture such as a crack or peeling on the transparent conductive thin film on the film electrode side. In addition, the transparent conductive thin film of the film electrode is sometimes broken at the time of bending the film electrode, for example, in a step of producing the touch panel or at the time of an input at an end portion of the touch panel. This breaking in the transparent conductive thin film is a phenomenon caused by insufficient flexibility of the transparent conductive thin film. In order to solve these problems, a transparent conductive film is required that attains both excellent pen sliding durability and flexibility.
A means for increasing the pen sliding durability includes a method of crystallizing the transparent conductive thin film on the film electrode side (for example, see PTD 1). In the conventional transparent conductive film, however, the crystallinity of an indium-tin composite oxide is controlled to realize a transparent conductive film excellent in pen sliding durability. The conventional transparent conductive film, however, has been insufficient when subjected to the flexibility test described below.